The Evolved Packet System (EPS) proposed by the 3rd Generation Partnership Project (3GPP) consists of Evolved Universal Terrestrial Radio Access Network (E-UTRAN), Mobility Management Entity (MME), Serving Gateway (S-GW), Packet Data Network Gateway (PDN-GW), Home Subscriber Server (HSS), Authentication, Authorization and Accounting (AAA) server of the 3GPP, Policy and Charging Rules Function (PCRF) entity and other supporting nodes. FIG. 1 shows a schematic diagram of the system architecture of the EPS according to the related art. As shown in FIG. 1, the MME takes charge of mobility management, processing of Non-Access layer signaling, user mobility management, context management and other related tasks at the control plane; The S-GW is an access gateway device connected to the E-UTRAN, transfers data between the E-UTRAN and the PDN-GW, and takes charge of caching paging waiting data; The PDN-GW (P-GW for short) is a border gateway between the EPS and the Packet Data Network (PDN), and takes charge of access to the PDN and data transfer between the EPS and the PDN; both the S-GW and the PDN-GW are core network gateways; The PCRF is connected to the Internet Protocol (IP) service network through a receiving interface Rx, so as to acquire service information. Moreover, the PCRF is also connected to a gateway device in the network through a Gx/Gxa/Gxc interface, takes charge of initiating of establishment of IP bearer, ensuring of Quality of Service (QoS) of service data, and charging control.
The EPS supports interworking of the 3GPP system with a non-3GPP system, wherein, the interworking is implemented via an S2a/b/c interface, and the PDN-GW serves as an anchor between the 3GPP system and the non-3GPP system. In the system architecture diagram of the EPS, the non-3GPP IP access network system is divided into a trusted non-3GPP IP access network and an untrusted non-3GPP IP access network. The trusted non-3GPP IP access network can be directly connected to the PDN-GW via the S2a interface; the untrusted non-3GPP IP access network may be connected to the PDN-GW via an Evolved Packet Data Gateway (ePDG); the S2b interface is used between ePDG and PDN-GW; the S2c interface provides both control and mobility support for a user plane and between a User Equipment (UE) and the PDN-GW, and supports the mobility management protocol, Mobile IPv6 Support for Dual Stack Hosts and Routers (DSMIPv6).
In the EPS system, the Policy and Charging Enforcement Function (PCEF) entity is located in the PDN-GW, and exchanges information with the PDN-GW via the Gx interface, as shown in FIG. 1. When the interface between PDN-GW and S-GW is based on PMIPv6, the S-GW includes a Bearer Binding and Event Report Function (BBERF) entity to process QoS control for service data flows, the S-GW exchanges information with the PCRF through the Gxc interface, as shown in FIG. 1. When the access is performed through the trusted non-3GPP access system, the BBERF may reside on the trusted non-3GPP access gateway. The trusted non-3GPP access gateway exchanges information with the PCRF via the Gxa interface, as shown in FIG. 1. When the UE is roaming, the S9*interface becomes an interface between a home PCRF and a visitor PCRF, and at the same time, provides Application Functions (AFs) of services for the UE. The S9*interface transmits service information for formulating the Policy and Charging Control (PCC) policy, to the PCRF via the Rx interface. In the 3GPP, a PDN network can be found by using its corresponding Access Point Name (APN). Connection of the UE to the PDN network is usually called an IP Connectivity Access Network (IP-CAN) session. In the process of establishing the IP-CAN session, each of the BBERF and the PCEF establishes a Diameter session with the PCRF, in order to transmit policy and charging information for controlling the IP-CAN session, information for formulating the policy and the like. Wherein, the Diameter session is based on the Diameter protocol, which is an upgraded version of the Remote Authentication Dial In User Service (RADIUS) protocol.
A corresponding Broadband Forum (BBF) has proposed a broadband policy control architecture, i.e., Broadband Policy Control Function (BPCF), as shown in FIG. 2. The BPCF is mainly used to formulate corresponding policies; a Policy Enforcement Point (PEF) usually resides in a transmitting device in the fixed network, such as a Broadband Remote Access Server (BRAS)/a Broadband Network Gateway (BNG), so as to implement the policy as formulated by the BPCF; the AAA server is configured to store user contract information. The AF formulates policies for the BPCF, and provides corresponding service information. Currently, the architecture of the BPCF is still rough, and related details are still being specified.
The Fixed Mobile Convergence (FMC) scenario, which has become a great concern of the operators, is being researched based on interconnection and interworking between the 3GPP and the BBF. In the scenario of a user accessing the mobile core network through the BBF fixed network, the QoS on all routing paths of data (which will pass through the fixed network and the mobile network) needs to be guaranteed. At the present stage, this is performed by using the S9*interface, which is located between the PCRF and the BPCF. To operate services better and broaden the wireless coverage, a mobile operator may hire a piece of line accessing a Wireless Local Area Network (WLAN) from a fixed network operator, considering cost saving. In the case that the UE performs access through the WLAN of the fixed network, as transmission of the data will pass through the fixed network, the UE will establish an IP security (IP-Sec) tunnel with the ePDG when the mobile operator regards the network provided by the fixed network operator as untrusted, so as to ensure that the data transmitted between the UE and the ePDG is encrypted, and the contents being transmitted cannot be learned by the transmitting device in the fixed network. In the related art, there are two practical deployment modes as follows.
Mode 1: as shown in FIG. 3, the UE accesses the Residential Gateway (RG) through the WiFi access point, and accesses the Broadband Remote Access Server (BRAS) or BNG through an Access Note (AN), such as a Digital Subscriber Line Access Multiplexer (DSLAM). Since in this case, the IP address of the UE is assigned by the RG while the IP address of the RG is assigned by the BRAS/BNG, the RG needs to perform an IP address conversion. Wherein, the assigning of the IP address for the UE by the RG, may be implemented in the following way. For example, when the UE accesses the RG, the UE is authenticated on the RG by using its user name and password, and the RG assigns an internal address for the UE when authentication is passed. The assigning of the IP address for the RG by the BRAS/BNG may be implemented in the following way. For example, when the RG is powered on, the RG initiates authentication to the BRAS/BNG and the BRAS/BNG assigns an IP address for the RG.
Mode 2: as shown in FIG. 4, the UE performs access through a WiFi access point, and accesses the BRAS/BNG through an AN, wherein the IP address of the UE here is assigned by the BRAS/BNG. Wherein, for accessing the BRAS/BNG through an AN, of course there may be an RG between the AN and the BRAS/BNG when accessing, but to be different from mode 1, in this mode, the RG does not assign an IP address for the UE, the RG here is just a layer-two device not assigning an IP address for the UE, and the connections of the RG to the UE and the BRAS are layer-two connections.
For saving address space, the IP address assigned by the fixed network operator for the UE or the RG by using the BRAS/BNG may be a private IP address. In this case, the BRAS/BNG also needs to perform an IP address conversion.
In mode 2, as the BRAS/BNG assigns an IP address for the UE and authenticates the UE, and the BRAS/BNG is located in the BBF fixed network, the BBF fixed network may be aware of the access of UE to the WLAN, and the BPCF may also be aware of the access of UE to the WLAN, for example, the BPCF may be aware of the access of the UE to the WLAN through the BNG/BRAS or the BBF AAA, so that the BPCF may initiate establishment of an S9* session to the PCRF. However, in mode 1, the UE will not be authenticated on the BRAS/BNG when the UE accesses the WLAN through the RG, because the UE has been authenticated on the RG and the RG has assigned an IP address for the UE. Therefore, the BBF fixed network may not be aware of the access of UE to the WLAN, and the BPCF may not be aware of the access of UE to the WLAN, either. For example, when the UE transmits a message, the RG converts the source IP address of the UE of the message to a combination of the IP address of the RG itself and a certain port. Thus, it seems from the BRAS/BNG that the received IP message is the IP message from the RG, the particular UE behind the RG will not be detected, and accordingly, the BPCF cannot initiate an S9* session to the PCRF. In sum, in the related art, the S9* session cannot be initiated if the BPCF cannot be aware of the access of the UE to the WLAN, because the S9* session is initiated by the BPCF to the PCRF, and the premise for initiating the S9* session is that the BPCF must be aware of the access of the UE to the WLAN. A technical solution is needed, in which fixed network access information can be reported, such that an S9* session still can be established even if the BPCF cannot be aware of the access of the UE to the WLAN.